Semiconductor device and manufacturing method thereof

Abstract

A semiconductor device includes an epitaxial layer having a first conduction type, a base layer formed adjacent and on the epitaxial layer and having an opposite second conduction type to the first conduction type, a source layer formed selectively on the base layer and having the first conduction type, a trench which passes through the base layer and the source layer and which reaches the epitaxial layer, an insulation film formed along an interior wall of the trench, a control electrode formed within the trench via the insulation film, and a semiconductor region formed along the bottom part of the trench at the epitaxial layer and having the first conduction type.

1 . A semiconductor device comprising:
 an epitaxial layer having a first conduction type;   a base layer formed adjacent and on the epitaxial layer and having an opposite second conduction type to the first conduction type;   a source layer formed selectively on the base layer and having the first conduction type;   a trench which passes through the base layer and the source layer and which reaches the epitaxial layer;   an insulation film formed along an interior wall of the trench;   a control electrode formed within the trench via the insulation film; and   a semiconductor region formed along the bottom part of the trench at the epitaxial layer and having the first conduction type.   
   
   
       2 . The semiconductor device according to  claim 1 , wherein the semiconductor region has the same concentration of impurities as the epitaxial layer. 
   
   
       3 . The semiconductor device according to  claim 1 , wherein the concentration of impurities of the semiconductor region and the epitaxial layer is lower compared to the concentration of impurities of the source layer. 
   
   
       4 . The semiconductor device according to  claim 2 , wherein the concentration of impurities of the semiconductor region and the epitaxial layer is lower compared to the concentration of impurities of the source layer. 
   
   
       5 . The semiconductor device according to  claim 1 , wherein the bottom part of the trench is formed deeper from the base layer and the semiconductor region is arranged in a deeper position than the base layer. 
   
   
       6 . The semiconductor device according to  claim 4 , wherein the bottom part of the trench is formed deeper from the base layer and the semiconductor region is arranged in a deeper position than the base layer. 
   
   
       7 . The semiconductor device according to  claim 1 , wherein a side wall of the trench has a taper shape. 
   
   
       8 . A method of manufacturing a semiconductor device, the method comprising;
 forming a base layer by implanting second type conduction impurities into a first conduction type epitaxial layer using an ion implantation method;   forming a source layer by implanting first type conduction impurities into the base layer by the ion implantation method;   forming a trench to pass through the base layer and the source layer and to reach the epitaxial layer;   forming a first oxide film within the trench; and   forming a first conduction type semiconductor region by implanting first type conduction impurities using an ion implantation method into a bottom part of the trench after forming the first oxide film.   
   
   
       9 . The method of manufacturing a semiconductor device according to  claim 8 , further comprising removing the first oxide film after implanting the first type conduction impurities into the semiconductor region. 
   
   
       10 . The method of manufacturing a semiconductor device according to  claim 9 , wherein the first oxide film is a sacrificial oxide film. 
   
   
       11 . The method of manufacturing a semiconductor device according to  claim 8 , further comprising forming a second oxide film within the trench after removing the first oxide film. 
   
   
       12 . The method of manufacturing a semiconductor device according to  claim 11 , wherein the second oxide film is a gate insulation film.